W3C home > Mailing lists > Public > public-bpwg@w3.org > May 2009

Re: [agenda] Sprites for decorative images only

From: Alan Chuter <achuter@technosite.es>
Date: Wed, 20 May 2009 12:25:53 +0200
Message-ID: <4A13DAB1.4020604@technosite.es>
To: MWI BPWG Public <public-bpwg@w3.org>
CC: adamconnors@google.com, Bruce Lawson <brucel@opera.com>
Adam Connors wrote:
> So I update 3.4.6 BP in MWABP on Sprites to point out that using sprites is
> a popular technique to reduce network requests, but that it should only be
> used for decorative images (inline with [BP1 & WCAG refs])... ?

That was my understanding. But I have to apologise for commenting 
without doing enough research first. Sprites should be used, I believe, 
with replacement techniques (see Dave Shea's blog [1] for a survey of 
them). In that case the image is an alternative to the text. If CSS does 
not work for any reason, the text is displayed (as long as the whole 
sprite image isn't then filling up the window). so maybe this isn't the 
case after all.

[1] http://www.mezzoblue.com/tests/revised-image-replacement/

> Sounds good to me -- added to my todo list.
> On Wed, May 20, 2009 at 8:22 AM, Bruce Lawson <brucel@opera.com> wrote:
>> On Wed, 20 May 2009 08:02:53 +0100, Alan Chuter <achuter@technosite.es>
>> wrote:
>>   > We could point to WCAG 2; the "Techniques for WCAG 2" document says
>>>  > "Using CSS to include decorative images":
>>> I think that the WCAG technique is saying "if you want to use images that
>>> don't require alternative text, you can use CSS," but the BP says "use CSS
>>> to create sprite images" and should add "if you do this then you can't
>>> provide alternative text, so don't use sprites for non-decorative images."
>>> I think it would be useful to warn people to avoid failure F3: "Failure of
>>> Success Criterion 1.1.1 due to using CSS to include images that convey
>>> important information" [1]. I suspect that unfortunately this excludes much
>>> of the intended scope of the BP.
>> It's a Worst Practice to use sprites (or any CSS) to convey information.
>> b

Alan Chuter
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Received on Wednesday, 20 May 2009 10:28:49 UTC

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